Which metabolic shift offsets photorespiration after prolonged daytime stomata closure in some plants?

💡 Explanation

When stomata close to conserve water, CO2 levels deplete, leading to increased photorespiration. Enhanced PEP carboxylase activity initiates the C4 pathway, because it fixes CO2 efficiently even at low concentrations, minimizing wasteful photorespiration. Therefore C4 photosynthesis results, rather than ABA synthesis, or NADPH activation, downregulating Calvin which do not fix CO2 efficiently.

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